Java:由 HTTP 连接创建的等待连接线程存活时间很长

Question

我有一个服务器端代码，用于检查 SOAP 服务是否已启动。代码如下:

String response = "";

while (response.length() == 0) {
    try {
        final URL url = new URL("DummySoapServiceURL");
        final HttpURLConnection httpConnection = (HttpURLConnection) url.openConnection();
        InputStream inputStream = null;
        try {
            httpConnection.setRequestMethod("GET");

            inputStream = httpConnection.getInputStream();
            final byte[] buffer = new byte[BUFFER_SIZE];
            while (inputStream.read(buffer, 0, BUFFER_SIZE) != -1) {
                response = new String(buffer);
            }
        } finally {
            IOUtils.closeQuietly(inputStream);
            httpConnection.disconnect();
        }
    } catch (MalformedURLException e) {
        // error handling
    } catch (IOException e) {
        // error handling
    }
}

现在的问题是，每次检查都会创建大约 3-4 个连接线程。即使 SOAP 服务检查完成，这些线程仍处于 Activity 状态。这些线程的线程转储快照如下所示:

"http-host/ip:port-11" prio=10 tid=0x00000000064f0000 nid=0x32cc waiting on condition [0x00002b54bc604000]
   java.lang.Thread.State: WAITING (parking)
    at sun.misc.Unsafe.park(Native Method)
    - parking to wait for  <0x00000000d5093c78> (a java.util.concurrent.locks.AbstractQueuedSynchronizer$ConditionObject)
    at java.util.concurrent.locks.LockSupport.park(LockSupport.java:186)
    at java.util.concurrent.locks.AbstractQueuedSynchronizer$ConditionObject.await(AbstractQueuedSynchronizer.java:2043)
    at java.util.concurrent.LinkedBlockingQueue.take(LinkedBlockingQueue.java:442)
    at java.util.concurrent.ThreadPoolExecutor.getTask(ThreadPoolExecutor.java:1068)
    at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1130)
    at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:615)
    at org.apache.tomcat.util.net.NioEndpoint$DefaultThreadFactory$1$1.run(NioEndpoint.java:1249)
    at java.lang.Thread.run(Thread.java:744)
   Locked ownable synchronizers:
    - None

现在我不确定为什么这些连接线程正在等待/ parking 以及如何关闭它们。在我的代码中，打开的流被关闭，连接被使用disconnect()断开。

我还尝试设置以下 HTTP 属性:

httpConnection.addRequestProperty("Connection", "close");

但这并没有帮助。我怀疑 JAVA 有时可能会关闭这些线程。但我不知道，什么时候，如何？ JDK版本为jdk1.7.0_51_x64。请告诉我，如何阻止这些连接线程数的增加？

Answer 1

迁移了整个实现以使用 apache HTTP 客户端，因为它具有特殊的 API 以实现更好的控制。但这没有帮助。即使使用 apache HTTP 客户端，我也可以看到这些等待的连接线程。

终于找到关于redhat website for JBOSS HTTP connector configuration的提示。为HTTP连接器配置线程池并解决了问题:

<subsystem xmlns="urn:jboss:domain:threads:1.1"> 
    <thread-factory name="http-connector-factory" group-name="uq-thread-pool" thread-name-pattern="HTTP-%t" priority="9"/> 
    <unbounded-queue-thread-pool name="uq-thread-pool"> 
        <max-threads count="5"/> 
        <keepalive-time time="5" unit="seconds"/> 
        <thread-factory name="http-connector-factory"/> 
    </unbounded-queue-thread-pool> 
</subsystem> 

<subsystem xmlns="urn:jboss:domain:web:2.2" default-virtual-server="default-host" native="false">

    <connector name="http" protocol="org.apache.coyote.http11.Http11NioProtocol" scheme="http" socket-binding="http" executor="uq-thread-pool"/> 
    ....
    ....